// 定义成员：
const sum = function (a, b) {
  return parseInt(a) + parseInt(b)
}
const subtract = function (a, b) {
  return parseInt(a) - parseInt(b)
}
const multiply = function (a, b) {
  return parseInt(a) * parseInt(b)
}
const divide = function (a, b) {
  return parseInt(a) / parseInt(b)
}

//简写
module.exports = {
  sum,
  subtract,
  multiply,
  divide
}